The present invention relates to the general field of gas turbines and it relates more particularly to a method for monitoring the positive displacement efficiency of the high pressure (HP) pump of a hydraulic regulation system of a turbomachine without having recourse to using a specific sensor or system.
The field of application of the invention is that of gas turbines for engines for airplanes or helicopters that generally include a high pressure positive displacement pump for producing hydraulic energy, for feeding fuel to the engines, and for lubricating various accessories of the engine.
In known manner (e.g. from FR 2 923 871), the efficiency of the HP pump is monitored by the high pressure shutoff valve (HPSOV) that serves to pressurize the engines and that, given knowledge of the level of leakage in the hydraulic system, is capable of determining the level of leakage in the HP pump by subtracting the leaks due to other components in the system such as actuators, servo-valves, and various other intermediate valves.
Nevertheless, although that solution is entirely satisfactory for evaluating overall leakage in the system, it does not make it possible to track accurately the efficiency of the HP pump that varies as a result of degradation over time in the various components of the system and because the hydraulic control of the variable geometry vanes is not shut off at low speed, which raises a problem when it is necessary to evaluate the capacity of the system for enabling engines to be restarted in flight or when it is appropriate to plan for replacing the HP pump, without such replacement giving rise to any major operating impact.